The present invention relates to a carriage pre-load support and bushing system for a computer driven printer/plotter carriage which slides back and forth transversely of the path of paper travel through the printer/plotter on at least one smooth support rod which is ordinarily cylindrical.
Carriage bushing systems require high tolerance and low friction and have inherently conflicting design requirements since high tolerance bushing systems require dimensionally stable materials which usually have high coefficients of friction. Conversely, a bushing system which is constructed primarily of lubricous material for reduced friction tends to be dimensionally unstable. Low friction bushings can be manufactured to the required tolerances by secondary processing (i.e., coining) operations with repeated inspections and rejection of bushings that are not manufactured to the correct tolerance. Clearly, such operations materially increase the per part finished cost.
A carriage support system which can be manufactured to and retain close tolerances is therefore required for printer/plotter carriages which must move without impediment at a high rate of speed with frequent reversals in the direction of movement along the slider rods.